I think the time-scale argument lacks a little bit of imagination. Time scales are very relative. There could easily be organisms that have lifespans in the th

I think the time-scale argument lacks a little bit of imagination. Time scales are very relative. There could easily be organisms that have lifespans in the thousands of years due to a variety of unique selective pressures (or no concept of a lifespan at all). Or species that have technology that can augment their lifespans to be thousands of years long. I can certainly see humans getting to that point in the next 10-thousand years. Given a thousand year lifespan, what is a few hundred years in terms of commitment to a project? It would be something akin to working a job for 10 years or so, which is not entirely unheard of. The ROI argument is more interesting! Although there are way too many factors to consider to have a definitive answer one way or another.